This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A022303 #6 Apr 02 2016 22:48:23
%S A022303 1,2,1,2,2,1,2,2,1,1,2,1,1,2,2,1,2,1,1,2,1,2,2,1,1,2,1,1,2,1,2,2,1,2,
%T A022303 2,1,1,2,1,2,2,1,2,1,1,2,1,1,2,2,1,2,2,1,1,2,1,2,2,1,2,2,1,1,2,1,1,2,
%U A022303 1,2,2,1,2,1,1,2,2,1,2,2,1,1,2,1,2,2,1,2,2,1,1,2,1,1,2,2,1,2,1
%N A022303 The sequence a of 1's and 2's starting with (1,2,1) such that a(n) is the length of the (n+2)nd run of a.
%H A022303 Clark Kimberling, <a href="/A022303/b022303.txt">Table of n, a(n) for n = 1..20000</a>
%e A022303 a(1) =1, so the 3rd run has length 1, so a(4) must be 2.
%e A022303 a(2) = 2, so the 4th run has length 2, so a(5) = 2 and a(6) = 1.
%e A022303 a(3) = 1, so the 5th run has length 1, so a(7) = 2.
%e A022303 a(4) = 2, so the 6th run has length 2, so a(8) = 1 and a(9) = 1.
%e A022303 Globally, the runlength sequence of a is 1,1,1,2,1,2,2,1,2,2,1,1,2,1,...., and deleting the first two terms leaves a = A022303.
%t A022303 a = {1, 2}; Do[a = Join[a, ConstantArray[If[Last[a] == 1, 2, 1], {a[[n]]}]], {n, 100}]; a (* _Peter J. C. Moses_, Apr 02 2016 *)
%Y A022303 Cf. A022300, A006928, A000002.
%K A022303 nonn
%O A022303 1,2
%A A022303 _Clark Kimberling_
%E A022303 Clarified and augmented by _Clark Kimberling_, Apr 02 2016